Mythbusters, Plane on a treadmill..

[Bushhatesyou]

Looks like they are going to finally put this one to bed.

http://dsc.discovery.com/fansites/mythbusters/mythbusters.html

Click on the part that says Plane Peek, to see a clip of it.

 

[Kream926]

i cant wait that long...

 

[Amish RakeFight]

Not this again!

 

[samballs]

Well I guess I'll start it. Those of you that went to academys I know they don't teach you anything but how to use the GPS. The speed of the tires does not make the plane fly, it is the airflow over the wings.

 

[fugghedabowdit]

Why is this even a controversy?

 

[crusader 22]

Somebody was listening to Boortz today.

 

[PCL_128]

Looks like they are going to finally put this one to bed.

This one was put to bed a long time ago for anyone that is actually in possession of an IQ above 70.

 

[MALSR]

That has to violate part 91 somewhere.

 

[F/O]

There is some great debate over this? Let me get this straight...no relative wind over the wing and there are people out there that think the airplane could get airborne?

 

[Herman Bloom]

People get upset about this because the specifics of the "scenario" are never clear. The "trick" in this question is: the plane can accelerate down the huge treadmill regardless of the treadmill (and hence the wheel rotational) speed, assuming of course that the wheel bearings are "frictionless" and don't fly off due to their tremendous rotational speed (which would be proportional to the plane's forward velolcity PLUS the additional rotational velocity created by the treadmill). In other words, the plane's engines -- which push against the air -- can overcome the reverse velocity created by the treadmill because they are independent variables.

You know what, it is stupid to try to explain this. Forget it.

 

[PCL_128]

There is some great debate over this? Let me get this straight...no relative wind over the wing and there are people out there that think the airplane could get airborne?

Since when do the wheels of an airplane provide the force for forward momentum?

 

[blott]

The engines push a little bit-depending on the type of engine. But, don't the engines really pull?

(I'm going to watch the link now, just responding to comments here.... I.E. as usual, I have no Idea what I'm responding to.)

B

 

[Sig]

But, don't the engines really pull?

Another piece of good thinking! True! If thrust initiates (or instantiates) any point noseward from furthest aft part of the machine, then they are tractors.

You must have been a real bear for physics teachers' "gotcha games."

 

[blott]

ok, watched the clip. I was going to flame "Herman" because his information is completely BS, as usual for FI posts. Then, I had a moment of clarity, (very rare these days for me). Herman is actually right-with exception to the "frictionless bearing" comment. Somehow, I understand what you are saying?

This all leads to a higher level of understanding for me:

1. I could only have concluded this by being completely drunk.

More important:

2. I am now going to finish off the rest of the bottle because there is no way I should have been able to comprehend any of this to begin with had I been drunk enough.

3. Once I have reached the "proper blood/alcohol limit", I'll point out the problems with the "frictionless bearings".

4. If I can actually do that , then obviously #2 wasn't enough-at that point it will be time to implement "plan B", but, since I'm actually "B".... oh never mind..

B

B

 

[blott]

Sig,

(drank 1/2 the rest of the bottle)

Physics teachers had a great impact on me-they are the reason I think this way...

Now, my psychology teachers gave up after I told them they were a product of my mind-Im not sure if I'm dreaming, or in a coma, etc. But, I'm almost sure none of this is real-I've made it all up, in any case, you can't prove it to me-you can't even prove you can't prove it to me...(think about that) (sorry but you exist in my mind-as twisted as that may seem).

Now to the important stuff.

I hadn't even contemplated to "placement" of the engine. Damn, more variables.

I was just pointing out that an engine doesn't really "push" against the air. It "pulls" I.E. pressure is lower on the front of the propellor, or the compressor-hence it is pulled forward. The air accelerated "back" provides some force, regardless if it is a prop or a "jet", but the main force is the (triangle) delta P, that pulls. (speaking of "jets" low, med, high bi-pass determines how much force the air exiting the engine contributes to forward thrust. (best case example I can think of is a afterburner-100% thrust from air accelerating aft).

time to kill the bottle and try to make some sense of all this.

B

 

[Sig]

time to kill the bottle and try to make some sense of all this.

Your second worthwhile thought on this thread. ENJOY!

 

[Max Q]

A rubber band airplane and a treadmill put this one to bed ages ago. It's incredible how many people are so baffled by Newton's third law.

-Brett

 

[Herman Bloom]

ok, watched the clip. I was going to flame "Herman" because his information is completely BS, as usual for FI posts. Then, I had a moment of clarity, (very rare these days for me). Herman is actually right-with exception to the "frictionless bearing" comment. Somehow, I understand what you are saying?

Here's another way of thinking of it: Instead of an engine, pretend that some huge giant is standing in front of the treadmill holding a string attached to the front of the plane. His pulling of the string can be thought of as a surrogate for the force created by the engine. Now, regardless of how fast that treadmill runs, the giant can still cause the plane to move down the length of the treadmill -- to accelerate and gain "airspeed" -- because the action of his pulling (= the engine) is totally independent of the treadmill's speed.

As for the "frictionless bearing" thing, I'll give you that. One could argue that the extreme rotational velocity of the wheels would destroy them, and I was trying to eliminate that as a variable.

 

[go!ng for broke]

WTF The wheels and bearings can go fast man like real fast. No drag at all. If I drive my ford ranger 300,000 miles for 22 years at 55 mph and then go 100mph one night down a long hill looking for my wife who just drove away on my harley do the wheels fly off? Do the bearings go nuts? The plane will fly only if the trap does not suck up into the prop. Do pretty girls f@rt was better. I learned to fly in a plane similar to that. JO spins his wheels all the time and his airplanes still fly.

 

[Say Again Over]

Isn't the whole point of having a real fast tread mill, to keep the aircraft from moving forward? So considering no matter how fast a treadmill moves, it won't restrict an airplane from accelerating and it should fly, right?